Calculated Field in Visuals

Thank you for posting the question and the detailed explanation on what you are expecting. At present, it is not possible to format the value as percentage in the Donut chart and this is an expected behavior. As every slice already represents a percent of the total, so we do not format individual values as percentages additionally, to avoid confusion. However, to achieve your use case you can consider the below workaround:

• Create a calculated field with expression {column_name} * 100 where column_name is the column which has the values like 0.095
• On the analyses page add this calculated field to the Donut chart and choose “Add Metric”.
• Then navigate to “Field wells” > click on the calculated field > Format >More Formatting Options..
• In “More Formatting Options”, navigate to “Units” and add a '%' suffix manually.

Following the above steps you should be able to display the values as percentage in the Donut chart.